Various methods are performed in conventional art to reduce multiple reflection of an ultrasonic image (B mode image) that obstructs diagnosis. An example of the methods is a known method using spatial compounding, in which a plurality of B mode images obtained by varying a deflection angle of ultrasound transmission and reception are compounded by arithmetic mean. In addition, an application of the method is a known method of estimating a degree and a position of a multiple reflection echo component from a plurality of B mode images having different deflection angles, and adaptively controlling a weight in arithmetic mean based on an estimation result.
However, the above method of compounding a plurality of images having different deflection angles cannot avoid influence of reduction in amplitude in the case of increasing the deflection angle, due to restriction of element factors.